TNF receptor I is required for induction of macrophage heat shock protein 70

• Published in: American Journal of Physiology: Cell Physiology Vol. 281; no. 1; p. C241
• Main Authors: Heimbach, J K, Reznikov, L L, Calkins, C M, Robinson, T N, Dinarello, C A, Harken, A H, Meng, X
• Format: Journal Article
• Language: English
• Published: United States 01-07-2001
• Subjects: Animals; Cells, Cultured; Gene Expression Regulation; Hot Temperature; HSP70 Heat-Shock Proteins - biosynthesis; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Immunoblotting; Macrophages - metabolism; Mice; Mice, Knockout; Receptors, Tumor Necrosis Factor - genetics; Receptors, Tumor Necrosis Factor - metabolism; RNA - metabolism; Spleen - cytology; Tumor Necrosis Factor-alpha - genetics; Tumor Necrosis Factor-alpha - metabolism
• ISSN: 0363-6143
• DOI: 10.1152/ajpcell.2001.281.1.c241

Expression of heat shock proteins (HSP) is an adaptive response to cellular stress. Stress induces tumor necrosis factor (TNF)-alpha production. In turn, TNF-alpha induces HSP70 expression. However, osmotic stress or ultraviolet radiation activates TNF-alpha receptor I (TNFR-I) in the absence of TNF-alpha. We postulated that TNF-alpha receptors are involved in the induction of HSP70 by cellular stress. Peritoneal Mphi were isolated from wild-type (WT), TNF-alpha knockout (KO), and TNFR (I or II) KO mice. Cells were cultured overnight and then heat stressed at 43 +/- 0.5 degrees C for 30 min followed by a 4-h recovery at 37 degrees C. Cellular HSP70 expression was induced by heat stress or exposure to endotoxin [lipopolysaccharide (LPS)] as determined by immunoblotting. HSP70 expression induced by either heat or LPS was markedly decreased in TNFR-I KO Mphi, whereas TNFR-II KO Mphi exhibited HSP70 expression comparable to that in WT mice. Expression of HSP70 after heat stress in TNF-alpha KO Mphi was also similar to that in WT mice, suggesting that induction of HSP70 by TNFR-I occurs independently of TNF-alpha. In addition, levels of steady-state HSP70 mRNA were similar by RT-PCR in WT and TNFR-I KO Mphi despite differences in protein expression. Furthermore, the effect of TNFR-I appears to be cell specific, since HSP70 expression in splenocytes isolated from TNFR-I KO was similar to that in WT splenocytes. These studies demonstrate that TNFR-I is required for the synthesis of HSP70 in stressed Mphi by a TNF-independent mechanism and support an intracellular role for TNFR-I.